This invention relates to resin impregnation of fabric.
Fabric is impregnated with resin for a variety of purposes, one such being the production of board for constructional, heat and electrical insulation and other purposes. One example of such board is the board which carries printed electrical circuits, known as printed circuit board or p.c.b.
As a step in the manufacture of such board, fabric is impregnated with resin by being run through a bath of liquid resin and the impregnated fabric is then dried. Subsequently, layers of dried, impregnated fabric are hot pressed together to form whatever thickness of laminate is required. The usual fabrics are woven cottons, synthetics and glass fibre. The fabrics are usually subjected to a pre-treatment and pre-drying to condition them to pick-up and be wet by the resin.
The step of drying the impregnated fabric, so that the fabric can be rolled up or cut up and stacked, is done in a drying tower, the fabric being hauled up continuously out of the resin bath.